/******************************************************
The interface to the operating system file io

(c) 1995 Innobase Oy

Created 10/21/1995 Heikki Tuuri
*******************************************************/

#ifndef os0file_h
#define os0file_h

#include "univ.i"

#ifndef __WIN__
#include <dirent.h>
#include <sys/stat.h>
#include <time.h>
#endif

typedef struct fil_node_struct fil_node_t;

#ifdef UNIV_DO_FLUSH
extern ibool os_do_not_call_flush_at_each_write;
#endif /* UNIV_DO_FLUSH */
extern ibool os_has_said_disk_full;
extern ibool os_aio_print_debug;

extern ulint os_file_n_pending_preads;
extern ulint os_file_n_pending_pwrites;

extern ulint os_n_pending_reads;
extern ulint os_n_pending_writes;

#ifdef __WIN__

/* We define always WIN_ASYNC_IO, and check at run-time whether
   the OS actually supports it: Win 95 does not, NT does. */
#define WIN_ASYNC_IO

#define UNIV_NON_BUFFERED_IO

#endif

#ifdef __WIN__
#define os_file_t HANDLE
#else
typedef int os_file_t;
#endif

extern ulint os_innodb_umask;

/* If this flag is TRUE, then we will use the native aio of the
OS (provided we compiled Innobase with it in), otherwise we will
use simulated aio we build below with threads */

extern ibool os_aio_use_native_aio;

#define OS_FILE_SECTOR_SIZE 512

/* The next value should be smaller or equal to the smallest sector size used
on any disk. A log block is required to be a portion of disk which is written
so that if the start and the end of a block get written to disk, then the
whole block gets written. This should be true even in most cases of a crash:
if this fails for a log block, then it is equivalent to a media failure in the
log. */

#define OS_FILE_LOG_BLOCK_SIZE 512

/* Options for file_create */
#define OS_FILE_OPEN 51
#define OS_FILE_CREATE 52
#define OS_FILE_OVERWRITE 53
#define OS_FILE_OPEN_RAW 54
#define OS_FILE_CREATE_PATH 55
#define OS_FILE_OPEN_RETRY      \
  56 /* for os_file_create() on \
     the first ibdata file */

#define OS_FILE_READ_ONLY 333
#define OS_FILE_READ_WRITE 444
#define OS_FILE_READ_ALLOW_DELETE 555 /* for ibbackup */

/* Options for file_create */
#define OS_FILE_AIO 61
#define OS_FILE_NORMAL 62

/* Types for file create */
#define OS_DATA_FILE 100
#define OS_LOG_FILE 101

/* Error codes from os_file_get_last_error */
#define OS_FILE_NOT_FOUND 71
#define OS_FILE_DISK_FULL 72
#define OS_FILE_ALREADY_EXISTS 73
#define OS_FILE_AIO_RESOURCES_RESERVED \
  74 /* wait for OS aio resources      \
     to become available again */
#define OS_FILE_ERROR_NOT_SPECIFIED 75

/* Types for aio operations */
#define OS_FILE_READ 10
#define OS_FILE_WRITE 11

#define OS_FILE_LOG 256 /* This can be ORed to type */

#define OS_AIO_N_PENDING_IOS_PER_THREAD \
  32 /* Win NT does not allow more      \
     than 64 */

/* Modes for aio operations */
#define OS_AIO_NORMAL                        \
  21 /* Normal asynchronous i/o not for ibuf \
     pages or ibuf bitmap pages */
#define OS_AIO_IBUF                                              \
  22                  /* Asynchronous i/o for ibuf pages or ibuf \
                      bitmap pages */
#define OS_AIO_LOG 23 /* Asynchronous i/o for the log */
#define OS_AIO_SYNC                                \
  24 /* Asynchronous i/o where the calling thread  \
     will itself wait for the i/o to complete,     \
     doing also the job of the i/o-handler thread; \
     can be used for any pages, ibuf or non-ibuf.  \
     This is used to save CPU time, as we can do   \
     with fewer thread switches. Plain synchronous \
     i/o is not as good, because it must serialize \
     the file seek and read or write, causing a    \
     bottleneck for parallelism. */

#define OS_AIO_SIMULATED_WAKE_LATER      \
  512 /* This can be ORed to mode        \
in the call of os_aio(...),              \
if the caller wants to post several i/o  \
requests in a batch, and only after that \
wake the i/o-handler thread; this has    \
effect only in simulated aio */
#define OS_WIN31 1
#define OS_WIN95 2
#define OS_WINNT 3
#define OS_WIN2000 4

extern ulint os_n_file_reads;
extern ulint os_n_file_writes;
extern ulint os_n_fsyncs;

/* File types for directory entry data type */

enum os_file_type_enum
{
  OS_FILE_TYPE_UNKNOWN = 0,
  OS_FILE_TYPE_FILE, /* regular file */
  OS_FILE_TYPE_DIR,  /* directory */
  OS_FILE_TYPE_LINK  /* symbolic link */
};
typedef enum os_file_type_enum os_file_type_t;

/* Maximum path string length in bytes when referring to tables with in the
'./databasename/tablename.ibd' path format; we can allocate at least 2 buffers
of this size from the thread stack; that is why this should not be made much
bigger than 4000 bytes */
#define OS_FILE_MAX_PATH 4000

/* Struct used in fetching information of a file in a directory */
struct os_file_stat_struct
{
  char name[OS_FILE_MAX_PATH]; /* path to a file */
  os_file_type_t type;         /* file type */
  ib_longlong size;            /* file size */
  time_t ctime;                /* creation time */
  time_t mtime;                /* modification time */
  time_t atime;                /* access time */
};
typedef struct os_file_stat_struct os_file_stat_t;

#ifdef __WIN__
typedef HANDLE os_file_dir_t; /* directory stream */
#else
typedef DIR *os_file_dir_t; /* directory stream */
#endif

/***************************************************************************
Gets the operating system version. Currently works only on Windows. */

ulint os_get_os_version(void);
/*===================*/
/* out: OS_WIN95, OS_WIN31, OS_WINNT, or OS_WIN2000 */
/********************************************************************
Creates the seek mutexes used in positioned reads and writes. */

void os_io_init_simple(void);
/*===================*/
/***************************************************************************
Creates a temporary file. */

FILE *os_file_create_tmpfile(void);
/*========================*/
/* out: temporary file handle (never NULL) */
/***************************************************************************
The os_file_opendir() function opens a directory stream corresponding to the
directory named by the dirname argument. The directory stream is positioned
at the first entry. In both Unix and Windows we automatically skip the '.'
and '..' items at the start of the directory listing. */

os_file_dir_t os_file_opendir(
    /*============*/
    /* out: directory stream, NULL if
    error */
    const char *dirname,   /* in: directory name; it must not
                           contain a trailing '\' or '/' */
    ibool error_is_fatal); /* in: TRUE if we should treat an
                           error as a fatal error; if we try to
                           open symlinks then we do not wish a
                           fatal error if it happens not to be
                           a directory */
/***************************************************************************
Closes a directory stream. */

int os_file_closedir(
    /*=============*/
    /* out: 0 if success, -1 if failure */
    os_file_dir_t dir); /* in: directory stream */
/***************************************************************************
This function returns information of the next file in the directory. We jump
over the '.' and '..' entries in the directory. */

int os_file_readdir_next_file(
    /*======================*/
    /* out: 0 if ok, -1 if error, 1 if at the end
    of the directory */
    const char *dirname,   /* in: directory name or path */
    os_file_dir_t dir,     /* in: directory stream */
    os_file_stat_t *info); /* in/out: buffer where the info is returned */
/*********************************************************************
This function attempts to create a directory named pathname. The new directory
gets default permissions. On Unix, the permissions are (0770 & ~umask). If the
directory exists already, nothing is done and the call succeeds, unless the
fail_if_exists arguments is true. */

ibool os_file_create_directory(
    /*=====================*/
    /* out: TRUE if call succeeds,
    FALSE on error */
    const char *pathname,  /* in: directory name as
                           null-terminated string */
    ibool fail_if_exists); /* in: if TRUE, pre-existing directory
                           is treated as an error. */
/********************************************************************
A simple function to open or create a file. */

os_file_t os_file_create_simple(
    /*==================*/
    /* out, own: handle to the file, not defined
    if error, error number can be retrieved with
    os_file_get_last_error */
    const char *name,  /* in: name of the file or path as a
                       null-terminated string */
    ulint create_mode, /* in: OS_FILE_OPEN if an existing file is
                   opened (if does not exist, error), or
                   OS_FILE_CREATE if a new file is created
                   (if exists, error), or
                   OS_FILE_CREATE_PATH if new file
                   (if exists, error) and subdirectories along
                   its path are created (if needed)*/
    ulint access_type, /* in: OS_FILE_READ_ONLY or
                   OS_FILE_READ_WRITE */
    ibool *success);   /* out: TRUE if succeed, FALSE if error */
/********************************************************************
A simple function to open or create a file. */

os_file_t os_file_create_simple_no_error_handling(
    /*====================================*/
    /* out, own: handle to the file, not defined
    if error, error number can be retrieved with
    os_file_get_last_error */
    const char *name,  /* in: name of the file or path as a
                       null-terminated string */
    ulint create_mode, /* in: OS_FILE_OPEN if an existing file
                   is opened (if does not exist, error), or
                   OS_FILE_CREATE if a new file is created
                   (if exists, error) */
    ulint access_type, /* in: OS_FILE_READ_ONLY,
                   OS_FILE_READ_WRITE, or
                   OS_FILE_READ_ALLOW_DELETE; the last option is
                   used by a backup program reading the file */
    ibool *success);   /* out: TRUE if succeed, FALSE if error */
/********************************************************************
Opens an existing file or creates a new. */

os_file_t os_file_create(
    /*===========*/
    /* out, own: handle to the file, not defined
    if error, error number can be retrieved with
    os_file_get_last_error */
    const char *name,  /* in: name of the file or path as a
                       null-terminated string */
    ulint create_mode, /* in: OS_FILE_OPEN if an existing file
                   is opened (if does not exist, error), or
                   OS_FILE_CREATE if a new file is created
                   (if exists, error),
                   OS_FILE_OVERWRITE if a new file is created
                   or an old overwritten;
                   OS_FILE_OPEN_RAW, if a raw device or disk
                   partition should be opened */
    ulint purpose,     /* in: OS_FILE_AIO, if asynchronous,
                       non-buffered i/o is desired,
                       OS_FILE_NORMAL, if any normal file;
                       NOTE that it also depends on type, os_aio_..
                       and srv_.. variables whether we really use
                       async i/o or unbuffered i/o: look in the
                       function source code for the exact rules */
    ulint type,        /* in: OS_DATA_FILE or OS_LOG_FILE */
    ibool *success);   /* out: TRUE if succeed, FALSE if error */
/***************************************************************************
Deletes a file. The file has to be closed before calling this. */

ibool os_file_delete(
    /*===========*/
    /* out: TRUE if success */
    const char *name); /* in: file path as a null-terminated string */

/***************************************************************************
Deletes a file if it exists. The file has to be closed before calling this. */

ibool os_file_delete_if_exists(
    /*=====================*/
    /* out: TRUE if success */
    const char *name); /* in: file path as a null-terminated string */
/***************************************************************************
Renames a file (can also move it to another directory). It is safest that the
file is closed before calling this function. */

ibool os_file_rename(
    /*===========*/
    /* out: TRUE if success */
    const char *oldpath,  /* in: old file path as a
                          null-terminated string */
    const char *newpath); /* in: new file path */
/***************************************************************************
Closes a file handle. In case of error, error number can be retrieved with
os_file_get_last_error. */

ibool os_file_close(
    /*==========*/
    /* out: TRUE if success */
    os_file_t file); /* in, own: handle to a file */
/***************************************************************************
Closes a file handle. */

ibool os_file_close_no_error_handling(
    /*============================*/
    /* out: TRUE if success */
    os_file_t file); /* in, own: handle to a file */
/***************************************************************************
Gets a file size. */

ibool os_file_get_size(
    /*=============*/
    /* out: TRUE if success */
    os_file_t file,    /* in: handle to a file */
    ulint *size,       /* out: least significant 32 bits of file
                       size */
    ulint *size_high); /* out: most significant 32 bits of size */
/***************************************************************************
Gets file size as a 64-bit integer ib_longlong. */

ib_longlong os_file_get_size_as_iblonglong(
    /*===========================*/
    /* out: size in bytes, -1 if error */
    os_file_t file); /* in: handle to a file */
/***************************************************************************
Write the specified number of zeros to a newly created file. */

ibool os_file_set_size(
    /*=============*/
    /* out: TRUE if success */
    const char *name, /* in: name of the file or path as a
                      null-terminated string */
    os_file_t file,   /* in: handle to a file */
    ulint size,       /* in: least significant 32 bits of file
                      size */
    ulint size_high); /* in: most significant 32 bits of size */
/***************************************************************************
Truncates a file at its current position. */

ibool os_file_set_eof(
    /*============*/
    /* out: TRUE if success */
    FILE *file); /* in: file to be truncated */
/***************************************************************************
Flushes the write buffers of a given file to the disk. */

ibool os_file_flush(
    /*==========*/
    /* out: TRUE if success */
    os_file_t file); /* in, own: handle to a file */
/***************************************************************************
Retrieves the last error number if an error occurs in a file io function.
The number should be retrieved before any other OS calls (because they may
overwrite the error number). If the number is not known to this program,
the OS error number + 100 is returned. */

ulint os_file_get_last_error(
    /*===================*/
    /* out: error number, or OS error
    number + 100 */
    ibool report_all_errors); /* in: TRUE if we want an error message
                              printed of all errors */
/***********************************************************************
Requests a synchronous read operation. */

ibool os_file_read(
    /*=========*/
    /* out: TRUE if request was
    successful, FALSE if fail */
    os_file_t file,    /* in: handle to a file */
    void *buf,         /* in: buffer where to read */
    ulint offset,      /* in: least significant 32 bits of file
                       offset where to read */
    ulint offset_high, /* in: most significant 32 bits of
                   offset */
    ulint n);          /* in: number of bytes to read */
/***********************************************************************
Rewind file to its start, read at most size - 1 bytes from it to str, and
NUL-terminate str. All errors are silently ignored. This function is
mostly meant to be used with temporary files. */

void os_file_read_string(
    /*================*/
    FILE *file,  /* in: file to read from */
    char *str,   /* in: buffer where to read */
    ulint size); /* in: size of buffer */
/***********************************************************************
Requests a synchronous positioned read operation. This function does not do
any error handling. In case of error it returns FALSE. */

ibool os_file_read_no_error_handling(
    /*===========================*/
    /* out: TRUE if request was
    successful, FALSE if fail */
    os_file_t file,    /* in: handle to a file */
    void *buf,         /* in: buffer where to read */
    ulint offset,      /* in: least significant 32 bits of file
                       offset where to read */
    ulint offset_high, /* in: most significant 32 bits of
                   offset */
    ulint n);          /* in: number of bytes to read */

/***********************************************************************
Requests a synchronous write operation. */

ibool os_file_write(
    /*==========*/
    /* out: TRUE if request was
    successful, FALSE if fail */
    const char *name,  /* in: name of the file or path as a
                       null-terminated string */
    os_file_t file,    /* in: handle to a file */
    const void *buf,   /* in: buffer from which to write */
    ulint offset,      /* in: least significant 32 bits of file
                       offset where to write */
    ulint offset_high, /* in: most significant 32 bits of
                   offset */
    ulint n);          /* in: number of bytes to write */
/***********************************************************************
Check the existence and type of the given file. */

ibool os_file_status(
    /*===========*/
    /* out: TRUE if call succeeded */
    const char *path,      /* in:  pathname of the file */
    ibool *exists,         /* out: TRUE if file exists */
    os_file_type_t *type); /* out: type of the file (if it exists) */
/********************************************************************
The function os_file_dirname returns a directory component of a
null-terminated pathname string.  In the usual case, dirname returns
the string up to, but not including, the final '/', and basename
is the component following the final '/'.  Trailing '/' charac?
ters are not counted as part of the pathname.

If path does not contain a slash, dirname returns the string ".".

Concatenating the string returned by dirname, a "/", and the basename
yields a complete pathname.

The return value is  a copy of the directory component of the pathname.
The copy is allocated from heap. It is the caller responsibility
to free it after it is no longer needed.

The following list of examples (taken from SUSv2) shows the strings
returned by dirname and basename for different paths:

       path           dirname        basename
       "/usr/lib"     "/usr"         "lib"
       "/usr/"        "/"            "usr"
       "usr"          "."            "usr"
       "/"            "/"            "/"
       "."            "."            "."
       ".."           "."            ".."
*/

char *os_file_dirname(
    /*============*/
    /* out, own: directory component of the
    pathname */
    const char *path); /* in: pathname */
/********************************************************************
Creates all missing subdirectories along the given path. */

ibool os_file_create_subdirs_if_needed(
    /*=============================*/
    /* out: TRUE if call succeeded
       FALSE otherwise */
    const char *path); /* in: path name */
/****************************************************************************
Initializes the asynchronous io system. Creates separate aio array for
non-ibuf read and write, a third aio array for the ibuf i/o, with just one
segment, two aio arrays for log reads and writes with one segment, and a
synchronous aio array of the specified size. The combined number of segments
in the three first aio arrays is the parameter n_segments given to the
function. The caller must create an i/o handler thread for each segment in
the four first arrays, but not for the sync aio array. */

void os_aio_init(
    /*========*/
    ulint n,             /* in: maximum number of pending aio operations
                         allowed; n must be divisible by n_segments */
    ulint n_segments,    /* in: combined number of segments in the four
                         first aio arrays; must be >= 4 */
    ulint n_slots_sync); /* in: number of slots in the sync aio array */
/***********************************************************************
Requests an asynchronous i/o operation. */

ibool os_aio(
    /*===*/
    /* out: TRUE if request was queued
    successfully, FALSE if fail */
    ulint type,           /* in: OS_FILE_READ or OS_FILE_WRITE */
    ulint mode,           /* in: OS_AIO_NORMAL, ..., possibly ORed
                          to OS_AIO_SIMULATED_WAKE_LATER: the
                          last flag advises this function not to wake
                          i/o-handler threads, but the caller will
                          do the waking explicitly later, in this
                          way the caller can post several requests in
                          a batch; NOTE that the batch must not be
                          so big that it exhausts the slots in aio
                          arrays! NOTE that a simulated batch
                          may introduce hidden chances of deadlocks,
                          because i/os are not actually handled until
                          all have been posted: use with great
                          caution! */
    const char *name,     /* in: name of the file or path as a
                          null-terminated string */
    os_file_t file,       /* in: handle to a file */
    void *buf,            /* in: buffer where to read or from which
                          to write */
    ulint offset,         /* in: least significant 32 bits of file
                          offset where to read or write */
    ulint offset_high,    /* in: most significant 32 bits of
                     offset */
    ulint n,              /* in: number of bytes to read or write */
    fil_node_t *message1, /* in: messages for the aio handler (these
                         can be used to identify a completed aio
                         operation); if mode is OS_AIO_SYNC, these
                         are ignored */
    void *message2);
/****************************************************************************
Wakes up all async i/o threads so that they know to exit themselves in
shutdown. */

void os_aio_wake_all_threads_at_shutdown(void);
/*=====================================*/
/****************************************************************************
Waits until there are no pending writes in os_aio_write_array. There can
be other, synchronous, pending writes. */

void os_aio_wait_until_no_pending_writes(void);
/*=====================================*/
/**************************************************************************
Wakes up simulated aio i/o-handler threads if they have something to do. */

void os_aio_simulated_wake_handler_threads(void);
/*=======================================*/
/**************************************************************************
This function can be called if one wants to post a batch of reads and
prefers an i/o-handler thread to handle them all at once later. You must
call os_aio_simulated_wake_handler_threads later to ensure the threads
are not left sleeping! */

void os_aio_simulated_put_read_threads_to_sleep(void);
/*============================================*/

#ifdef WIN_ASYNC_IO
/**************************************************************************
This function is only used in Windows asynchronous i/o.
Waits for an aio operation to complete. This function is used to wait the
for completed requests. The aio array of pending requests is divided
into segments. The thread specifies which segment or slot it wants to wait
for. NOTE: this function will also take care of freeing the aio slot,
therefore no other thread is allowed to do the freeing! */

ibool os_aio_windows_handle(
    /*==================*/
    /* out: TRUE if the aio operation succeeded */
    ulint segment,                 /* in: the number of the segment in the aio
                                   arrays to wait for; segment 0 is the ibuf
                                   i/o thread, segment 1 the log i/o thread,
                                   then follow the non-ibuf read threads, and as
                                   the last are the non-ibuf write threads; if
                                   this is ULINT_UNDEFINED, then it means that
                                   sync aio is used, and this parameter is
                                   ignored */
    ulint pos,                     /* this parameter is used only in sync aio:
                                   wait for the aio slot at this position */
    fil_node_t **message1,         /* out: the messages passed with the aio
                                   request; note that also in the case where
                                   the aio operation failed, these output
                                   parameters are valid and can be used to
                                   restart the operation, for example */
    void **message2, ulint *type); /* out: OS_FILE_WRITE or ..._READ */
#endif

/* Currently we do not use Posix async i/o */
#ifdef POSIX_ASYNC_IO
/**************************************************************************
This function is only used in Posix asynchronous i/o. Waits for an aio
operation to complete. */

ibool os_aio_posix_handle(
    /*================*/
    /* out: TRUE if the aio operation succeeded */
    ulint array_no,        /* in: array number 0 - 3 */
    fil_node_t **message1, /* out: the messages passed with the aio
                           request; note that also in the case where
                           the aio operation failed, these output
                           parameters are valid and can be used to
                           restart the operation, for example */
    void **message2);
#endif
/**************************************************************************
Does simulated aio. This function should be called by an i/o-handler
thread. */

ibool os_aio_simulated_handle(
    /*====================*/
    /* out: TRUE if the aio operation succeeded */
    ulint segment,                 /* in: the number of the segment in the aio
                                   arrays to wait for; segment 0 is the ibuf
                                   i/o thread, segment 1 the log i/o thread,
                                   then follow the non-ibuf read threads, and as
                                   the last are the non-ibuf write threads */
    fil_node_t **message1,         /* out: the messages passed with the aio
                                   request; note that also in the case where
                                   the aio operation failed, these output
                                   parameters are valid and can be used to
                                   restart the operation, for example */
    void **message2, ulint *type); /* out: OS_FILE_WRITE or ..._READ */
/**************************************************************************
Validates the consistency of the aio system. */

ibool os_aio_validate(void);
/*=================*/
/* out: TRUE if ok */
/**************************************************************************
Prints info of the aio arrays. */

void os_aio_print(
    /*=========*/
    FILE *file); /* in: file where to print */
/**************************************************************************
Refreshes the statistics used to print per-second averages. */

void os_aio_refresh_stats(void);
/*======================*/

#ifdef UNIV_DEBUG
/**************************************************************************
Checks that all slots in the system have been freed, that is, there are
no pending io operations. */

ibool os_aio_all_slots_free(void);
/*=======================*/
#endif /* UNIV_DEBUG */

/***********************************************************************
This function returns information about the specified file */
ibool os_file_get_status(
    /*===============*/
    /* out: TRUE if stat information found */
    const char *path,           /* in:  pathname of the file */
    os_file_stat_t *stat_info); /* information of a file in a directory */

#endif
